Water Pumps for Aquaponics: How to Choose the Right Size for Your System

It is no wonder why Aquaponics is quickly becoming a popular alternative to traditional farming.

It is extremely water-efficient, requiring 20 times less the amount of traditional farming methods due to its re-circulation of water.

Aquaponics is a closed-loop system which allows live fish and plants to coexist, applying the benefits and eliminating the drawbacks of both hydroponics and aquaculture.

While the human heart is the machine that supports the entire body with oxygen and nutrients, the water pump is the vital organ that provides the fish and the plants with their necessary nutrients as well.

In this article, we'll cover:

The role of a water pump in an aquaponics system and why it is important

The different types of water pumps and how to choose the type and size for your system

What are the best water pumps for aquaponics, why are they good, and where can I purchase one?

What is the Role of a Water Pump in an Aquaponics System?

The effectiveness of any water system is highly dependent on the quality of the components that make up the system. The importance of investing in high-quality, well-built parts for your aquaponics system cannot be overstressed. One of the most important and fundamental components of an aquaponics system is the water pump.

Water is the main medium in an aquaponics system as it is what supplies both plants and fish with water. In a typical media-filled aquaponics system, fish are kept in a fish tank while the plants remain in a grow bed. The only contact the tank and the grow bed have with each other is via the water which circulates through both vessels.

As fish consume food they leave waste in their tank. The water containing ammonia-filled waste is pumped from the fish tank into the grow bed where nitrifying bacteria break down the ammonia into plant food. After the plants absorb the plant food, the water from the grow bed (which is now fresh and favorable for fish) is then pumped back to the fish tank where the cycle begins all over.

The water pump plays a very important role in the aquaponics process as it ensures that both fish and plants receive their necessary nutrients for growth. The wrong sized or faulty pump can result in inadequate or excessive nutrients which can lead to the death of the fish or plants.

Why Do We Need One?

Water pumps play the important role of making sure the water in an aquaponic system circulates perfectly to maximize the effectiveness of the system. Their main purpose is to circulate the flow of water so that both plants and fish receive their required nutrients. Water pumps also raise the water level to the required height for your system. This is especially necessary when using a vertical aquaponic system wherein water needs to be lifted from the fish tank below to the grow bed which is placed higher up.

Because water is the lifeblood which flows through the system and provides essential nutrients to all the living organisms, a water pump can be thought of as the heart of the entire aquaponics system. If the heart is pumping too quickly, too slowly, not powerfully enough, or worse yet, shuts down entirely, the other organs depending on it for circulation will suffer immediately. A good reliable pump will give you peace of mind while you leave the system unattended at times. Also, while most aquaponics systems only require one pump to circulate the water, it is important to always have a backup for emergency purposes.

Type of Water Pumps

While there is a vast array of pump brands available for purchase, it is important to note that all these pumps fall into one of two major categories – the inline pumps and the submersible pumps.

Submersible Pumps - As the name suggests, these pumps sit directly in the reservoir or tank and pump water through a hose attached to a fitting at the top of the pump. They are sized in Gallons Per Hour (GPH) and their ability to work while being submerged in water also helps in cooling them off. They are limited in the amount of gallons of water that can be circulated and are preferred for smaller aquaponics systems that don’t exceed 1,200 GPH.

Submersible pumps are most common among household aquaponics systems and small commercial systems. A major advantage of the submersible pump is the fact that they are not prone to the pump cavitation problem, an issue usually associated with a high elevation difference between the surface of the fluid being pumped and the fluid itself.

Inline Pumps - Also referred to as centrifugal pumps, these air-cooled pumps sit outside your reservoir or tank and are preferred for larger aquaponic systems with over 50 towers. Because of their higher-powered motors they are capable of moving larger volumes of water. Their power is, however, measured in horsepower (HP) and not by the volume of water they can move. Inline pumps usually have a tube from the fish tank to the pump and another from the pump to the grow bed.

One major advantage of this pump type is that the heat generated by the pump is cooled by air as opposed to the submersible pump which is water-cooled. Also, inline pumps can be used to aerate water by pumping low volumes of air, usually at a high pressure into the water. This helps in avoiding anaerobic decomposition and supplying root zones with oxygen. Because of their ability to pump large volumes of water, they are mostly used in large commercial aquaponic systems

How to Determine the Right Size for Your System

In determining the correct pump size for your aquaponic system, there are three main steps that need to be done: determine the GPH, measure the head height, and combine the GPH and head height.

Determining GPH (Gallons Per Hour)

When sizing the water pump for your aquaponics system, the first thing we need to determine is GPH, or Gallons Per Hour. Almost all pumps have a Gallon Per Hour (GPH) rating that lets you know the number of gallons of water that it is able to pump every hour. In areas that use the metric system, the rating will be in Liters Per Hour.

As a general rule, your water pump should circulate the entire volume of the water in your aquaponic system at least every two hours. The pump you choose should meet this minimum requirement of cycling half of the entire system’s volume of water every hour.

For example:

If You have a 100 gallons of water in your system.

You will need a pump that can circulate at least 50 gallons of water per hour.

Thus, you will be looking for a pump with AT LEAST 50 GPH

Measuring head height

The majority of aquaponics systems have the fish tank and grow bed sitting at different levels. The head height is simply the distance between the water level of the fish tank and the desired water level of the grow bed.

Measuring the head height of your aquaponic system requires no calculation. You can simply measure the distance between the two water levels with a tape measure or ruler. Keep in mind that the larger the head, the more energy required to pump water. As a general rule, it takes about 1 PSI to raise the water level 2.2 feet. Keeping the head at a minimum level will keep the entire system as efficient as possible. Some aquaponic systems, where the water in the fish tank and the grow bed are at the same level or share the same container, have no “head.”

Combining GPH and Head Height

Once you have calculated your GPH and measured your head height, the final step in determining the right pump size for your system is combining the two variables. Generally, most water pumps come with a chart that combines that GPH and head height. The presentation of these charts varies according to brand and type (inline versus submersible).

This is an example of a chart for the Active Aqua Submersible Pump and should only be followed if using the Active Aqua Pump. Each manufacturer will have their own specific chart that comes with the product. Following a chart from another pump manufacturer can lead to inaccuracies.

These chart sheets come in the form of a graph with head height plotted on the vertical axis (y-axis) and GPH plotted on the horizontal axis (x-axis). To determine the right pump size, simply use your GPH and head height. Most inline pumps also come with curves showing the intersection points between GPH and head heights.

Thus, the intersection between your GPH with head height equals the perfect water pump size for your aquaponics system.

Things to Consider When Choosing a Pump

Here are some other things to take into consideration when choosing your pump.

Wattage used

It is important to know the electrical consumption of the pump you plan on purchasing. This means knowing the number of watts your water pump uses. Despite the fact that aquaponics has proven to be a cost-efficient method of farming with a relatively lower cost of capital when compared to other methods of farming, it still has some costs, one of which is the cost of energy used to run the pump – electricity. It is, therefore, important to get a water pump that gets the job done while using the smallest amount of energy possible. Knowing the wattage of your pump is the first step to making sure you do not purchase a pump that will end up consuming a large amount of electricity.

The simplest way to know the wattage for your water pump is to look at the electronic specs on the packet or instruction leaflet that accompanies the pump. Lower wattage means less consumption which in turn means less money being used on settling your electricity bills, especially since the water pump is going to be running consistently around the clock.

Flow Rate

After taking into consideration the wattage of the pump, the next thing to consider will be the amount of the water that has to be pumped through the system. As a general rule of thumb, your water pump should be able to circulate the entire system within two hours. So if your aquaponic system uses a 200-gallon setup, then it should be able to pump 200 gallons within two hours, or 100 gallons within 1 hour. So you would need a pump with at least 100 GPH. The GPH listed on a water pump is its maximum flow rate and can always be dialed down. It is therefore important to select a pump with a larger GPH than your required mount, never lesser.

This will ensure that your fish are supplied with clean and oxygenated water and that nutrient-rich water flows to your plants and nitrifying bacteria at least once every 2 hours. However, it is important to note that due to gravity, the pump flow rate tends to decrease as the vertical distance between the pump and the fluid surface increases.

In order to maintain an effective system, it is therefore important to buy a water pump that is strong enough to produce the required flow rate for your system.

What are the Best Water Pumps I Should Buy for My Aquaponics System?

The Homasy Submersible Pump features an adjustable flow rate knob with a maximum flow rate of 400 GPH. The 25Watt high-efficiency motor has the power to lift water 6.9 ft. It comes with a stainless steel impeller shaft for long life and corrosion resistance. The bottom of the pump has 4 strong suction cups to adhere to any flat surface. With a 12-month warranty, this pump is well-reviewed by many aquaponics enthusiasts.

Kedsum's submersible pump features an ultra-quiet motor that lifts water to a maximum of 4 feet. The small 20 Watt motor has 4 strong suction cups to adhere to any flat surface in the tank. It features two outlet adapters to fit the threading of your need and a 4.2 foot power cord. The Kedsum submersible pump is detachable and very easy to clean.

Ponics Pump's 400GPH submersible pump has a polished aluminum oxide ceramic impeller shaft to ensure long life and eliminate corrosion. The epoxy resin encasement protects the inner parts of the magnetic wet-rotor. Water-Lubricated Nitrile Bushings are used due to their low coefficient of friction. Features a 1 year limited warranty.

Conclusion

The water pump is one of the most critical components of a successful aquaponics system and should be treated as such. Be sure to do the required amount of research on your system before purchasing a pump. When you do purchase one, be sure to buy two of them: one to use for the tank, and one to keep for back up just in case the other one goes out.

Thank you for taking the time to read our article on the water pumps for aquaponics systems. We'd love to hear your feedback in the comments section below. If you've found this article to be useful and are interested in learning more, be sure to sign up for our newsletter.